scholarly journals The scattering of α-particles by matter

1910 ◽  
Vol 83 (565) ◽  
pp. 492-504 ◽  
Keyword(s):  
Quantitative Measurement ◽  
Direct Evidence ◽  
Zinc Sulphide ◽  
The Other ◽  
Narrow Slit ◽  
Preliminary Note ◽  
Metal Foils ◽  
Strong Source ◽  
Α Particles

In a preliminary note (‘Roy. Soc. Proc.’ A, vol. 81, p. 174, 1908) on the above subject, experiments were described which gave direct evidence of the scattering of the α -particles. In those experiments a strong source of α -radiation was placed at one end of a long exhausted tube, and the α -particles, after passing through a narrow slit, fell upon a zinc sulphide screen sealed to the other end of the tube. When the pressure inside the tube was very low, the narrow line of scintillations which marked the place of incidence of the α -particles on the screen was well defined, but when the rays on their way to the screen passed through gas or through thin metal foils the edges of this line of scintillations became indistinct. The amount of scattering could be estimated for different foils by placing them in the path of the rays and noting the distribution of the scintillations on the screen. The present investigation was undertaken with a view to obtain a quantitative measurement of the scattering by determining the most probable angle through which an α -particle of definite range is turned by passing through a given thickness of matter. The following are the chief points investigated:— (1) Determination of the amount of scattering produced in different thicknesses of the same material. (2) Comparison of the amounts of scattering produced in different materials. (3) Relation between the velocity of the α -particles and the amount of their scattering.

scholarly journals The decrease in velocity of α particles from radium C

1927 ◽  
Vol 114 (767) ◽  
pp. 341-354 ◽  
Keyword(s):  
Unit Length ◽  
Zinc Sulphide ◽  
Velocity Curve ◽  
Average Charge ◽  
Strong Magnetic Fields ◽  
Metal Foils ◽  
True Shape ◽  
Absorbing Material ◽  
Residual Gas ◽  
Α Particles

The early measurements of the decrease of velocity of α particles in passing through matter were made by Rutherford and Geiger, using the magnetic deflection method and observing by means of a zinc sulphide screen. The lowest velocities recorded were 0·43 V 0 by Rutherford and 0·2 V 0 by Geiger. Later Marsden and Taylor, using the same method, made measurements with air, mica and metal foils as the absorbing materials. It appeared from their experiments that something abnormal happened when the velocity had been reduced to about 0·415 V 0 , for as the thickness of absorbing material was increased beyond this point, the observed velocity remained unaltered. The simplest explanation of this is that these early experiments were probably carried out with a residual gas pressure high enough for the exchange He ++ ⇆ He + to be frequent. Under these conditions it can readily be shown from the data given by Rutherford for capture and loss of electrons by α particles that when the velocity lies between 0·4 V 0 and 0·3 V 0 the deflection in a magnetic field remains practically constant and equal to that of He ++ with a velocity of 0·4 V 0 . The problem of the true shape of the velocity curve towards the end of the range has been attacked in a number of ways. Kapitza measured the energy of a beam of α particles at points along the range by the heating effect. He has also examined by the Wilson cloud method the curvature of α ray tracks in very strong magnetic fields. From this data, by calculating the average charge on the α particle from Rutherford’s experiments mentioned above, he deduced the velocity curve for the region between 5 and 20 mm. from the end of the range in air. I. Curie has assumed that the rate of loss of energy for a single α particle is proportional to the number of ions produced per unit length of the path, and from her measurements of the ionisation or Bragg curve for a beam of rays and measurements of the straggling, she has deduced the form of the Bragg curve for a single average α particle. From this she has calculated on the above assumption the form of the velocity curve over the whole range. Blackett has also deduced the form of the velocity curve near the end of the range from the scattering observed by the Wilson cloud method.

Separation of Vitamins D2 and D3 as Isotachysterols D2 and D3 by Gas-Liquid Chromatography

1968 ◽  
Vol 51 (4) ◽  
pp. 834-838
Author(s):  
A J Sheppard ◽  
Denis E Lacroix ◽  
A R Prosser
Keyword(s):  
Liquid Chromatography ◽  
Quantitative Determination ◽  
Infrared Absorption ◽  
Quantitative Measurement ◽  
Acetyl Chloride ◽  
Internal Standard ◽  
The Other ◽  
Gas Liquid Chromatography ◽  
Absorption Data

Abstract A method for the quantitative determination of 0.5—20 μg vitamins D2 and D3 by gas-liquid chromatography is described. Vitamins D2 and D3 are completely isomerized to their respective isotachysterol isomers by acetyl chloride as demonstrated by ultraviolet and infrared absorption data. Dihydrotachysterol D2, isotachysterol D2, and isotachysterol D3 are completely resolved with a 3% JXR on 100-120 mesh Gas Chrom Q column packing. Calibration studies show that each compound exhibited a characteristic dose-response plot. Therefore, one isomer cannot be used as a direct internal standard for the quantitative measurement of the other isomer.

scholarly journals Note on the scattering of α-particles

1912 ◽  
Vol 86 (586) ◽  
pp. 235-240 ◽  
Keyword(s):  
Thin Film ◽  
Direct Determination ◽  
Single Scattering ◽  
Zinc Sulphide ◽  
Single Collision ◽  
Α Particles

In a previous paper on the scattering of the α -particles by matter the author has described experiments which allowed a direct determination of the most probable angle through which an α -particle is defected when passing through a thin film of matter.* In these experiments an intense, narrow and parallel pencil of α -particles was allowed to fall on a zinc sulphide screen, and the distribution of the scintillations over that screen was determined when tire pencil was intercepted by sheets of metal of various thickness and material. Measurements were also made for α -particles of varying speed, From this distribution the most probable defection suffered by the α -particle in each particular case was easily deduced. These deductions were based on the assumption that the scattering of the pencil is the result of a multitude of small defections suffered by the α -particles in their encounters with the atoms of the scattering foil. This type of scattering has recently been termed by Rutherford "compound scattering" in order to distinguish it from another type, denoted as "single scattering," which concerns the defections through large angles of an α -particle in a single collision. The first section of this paper deals with the distribution of the scattered α -particles on the screen; the second discusses the connection between the thickness of foils and the most probable angle of scattering which they produce. It will not be necessary to made any special assumptions as to the laws of action and reaction between the atom and the α -particle; it suffices only to suppose that the defection in each single collision is small compared with the final defection after passing through the scattering foil. This paper, therefore, does not deal with the large scattering observed by Geiger and Marsden which has been ascribed by Rutherford to single collisions. Such large defections are rare, and can be neglected in the consideration of the defections through small angles.

scholarly journals Some experiments concerning the counting of scintillations produced by alpha particles.— Part II. The determination of the efficiency of transformation of the kinetic energy of α-Particles into radiant energy

1929 ◽  
Vol 122 (789) ◽  
pp. 320-334 ◽  
Keyword(s):  
Kinetic Energy ◽  
Visible Light ◽  
Radiant Energy ◽  
Luminous Efficiency ◽  
Zinc Sulphide ◽  
Alpha Particles ◽  
Very High ◽  
Α Particles

The efficiency of zinc-sulphide in transforming the energy of α-particles into radiant energy was first investigated by Marsden who measured the amount of energy radiated as visible light from zinc-sulphide crystals bombarded by α-particles. The value of the efficiency obtained was 1∙5 per cent, though he considered this an under-estimate. The authors of this work were informed by Prof. Wertenstein, of Warsaw, that he had made some approximate determinations of the luminous efficiency of zinc-sulphide and obtained a very high value of 10 or 15 per cent. Prof. Wertenstein, however, considered these figures as merely a rough estimate and not necessarily reliable.

Part III Presumptions and Inferences, 6 Evidentiary Presumptions

2018 ◽  
Author(s):  
Sourgens Frédéric Gilles ◽  
Duggal Kabir ◽  
Laird Ian A
Keyword(s):  
Direct Evidence ◽  
The Other ◽  
Circumstantial Evidence ◽  
General Practices ◽  
Court Proceedings

This chapter considers presumptions, which serve as an efficiency or prudential function in court proceedings. Tribunals can make findings of fact by reference to presumptions. The use of presumptions means that the tribunal makes a determination of fact that is not premised upon direct evidence or project-specific circumstantial evidence. The tribunal instead is convinced of the truth of a fact premised upon the proof of relevant general surrounding circumstances. The use of presumptions is ubiquitous in investor-state arbitrations, as it is in other domestic and international disputes, because the predicate of a legal claim typically is the asserted deviation by one or both the parties of relevant general practices or expected background circumstances by the other.

scholarly journals The electrostatic deviation of α-rays from radio-tellurium

1906 ◽  
Vol 78 (521) ◽  
pp. 77-79 ◽  
Keyword(s):  
Thin Layer ◽  
Photographic Plate ◽  
Glass Plate ◽  
Zinc Sulphide ◽  
The Other ◽  
General Plan ◽  
Fluorescent Screen

A determination of the electrostatic deviation of the α -rays from radio-tellurium was suggested to the writer by Professor J. J. Thomson, as a continuation of the work on α-rays done by Professor A. S. Mackenzie. The general plan of the work was to let a beam of the rays pass between two charged plates, and then fall upon a glass plate coated with a thin layer of zinc sulphide on the side receiving the radiation. A photographic plate in contact with the other side of this fluorescent screen would be affected by the scintillations and thus mark the position of the beam.

Determination of the lattice translation across {110} APBs in GaAs

1988 ◽  
Vol 46 ◽  
pp. 600-601
Author(s):  
D.R. Rasmussen ◽  
N.-H. Cho ◽  
C.B. Carter
Keyword(s):  
Grain Boundaries ◽  
Lower Energy ◽  
Antiphase Boundary ◽  
The Other ◽  
Boundary Structure ◽  
Interface Plane ◽  
Inversion Symmetry ◽  
High Angle ◽  
Equilibrium Distance

Domains in GaAs can exist which are related to one another by the inversion symmetry, i.e., the sites of gallium and arsenic in one domain are interchanged in the other domain. The boundary between these two different domains is known as an antiphase boundary [1], In the terminology used to describe grain boundaries, the grains on either side of this boundary can be regarded as being Σ=1-related. For the {110} interface plane, in particular, there are equal numbers of GaGa and As-As anti-site bonds across the interface. The equilibrium distance between two atoms of the same kind crossing the boundary is expected to be different from the length of normal GaAs bonds in the bulk. Therefore, the relative position of each grain on either side of an APB may be translated such that the boundary can have a lower energy situation. This translation does not affect the perfect Σ=1 coincidence site relationship. Such a lattice translation is expected for all high-angle grain boundaries as a way of relaxation of the boundary structure.

Determination of the Burgers vector of a dislocation in a Fe-Mn alloy by weak-beam image in HVEM

1978 ◽  
Vol 36 (1) ◽  
pp. 330-331
Author(s):  
Y. Ishida ◽  
H. Ishida ◽  
K. Kohra ◽  
H. Ichinose
Keyword(s):  
High Order ◽  
Simulation Technique ◽  
The Other ◽  
Image Simulation ◽  
Diffraction Vector ◽  
Burgers Vector ◽  
Weak Beam ◽  
Beam Image ◽  
Edge Component

IntroductionA simple and accurate technique to determine the Burgers vector of a dislocation has become feasible with the advent of HVEM. The conventional image vanishing technique(1) using Bragg conditions with the diffraction vector perpendicular to the Burgers vector suffers from various drawbacks; The dislocation image appears even when the g.b = 0 criterion is satisfied, if the edge component of the dislocation is large. On the other hand, the image disappears for certain high order diffractions even when g.b ≠ 0. Furthermore, the determination of the magnitude of the Burgers vector is not easy with the criterion. Recent image simulation technique is free from the ambiguities but require too many parameters for the computation. The weak-beam “fringe counting” technique investigated in the present study is immune from the problems. Even the magnitude of the Burgers vector is determined from the number of the terminating thickness fringes at the exit of the dislocation in wedge shaped foil surfaces.

A quantitative image analysis method for the determination of cocontinuity in polymer blends

1993 ◽  
Vol 51 ◽  
pp. 894-895
Author(s):  
William A. Heeschen
Keyword(s):  
Image Analysis ◽  
Polymer Blends ◽  
Quantitative Measurement ◽  
Morphological Evolution ◽  
Phase Ratio ◽  
Irregular Shapes ◽  
Quantitative Image ◽  
Discrete Domains ◽  
A Domains

Two new morphological measurements based on digital image analysis, CoContinuity and CoContinuity Balance, have been developed and implemented for quantitative measurement of morphology in polymer blends. The morphology of polymer blends varies with phase ratio, composition and processing. A typical morphological evolution for increasing phase ratio of polymer A to polymer B starts with discrete domains of A in a matrix of B (A/B < 1), moves through a cocontinuous distribution of A and B (A/B ≈ 1) and finishes with discrete domains of B in a matrix of A (A/B > 1). For low phase ratios, A is often seen as solid convex particles embedded in the continuous B phase. As the ratio increases, A domains begin to evolve into irregular shapes, though still recognizable as separate domains. Further increase in the phase ratio leads to A domains which extend into and surround the B phase while the B phase simultaneously extends into and surrounds the A phase.

Procedures for the Quantitative Determination of Autoprothrombin C

1962 ◽  
Vol 08 (03) ◽  
pp. 434-441 ◽  
Author(s):  
Edmond R Cole ◽  
Ewa Marciniak ◽  
Walter H Seegers
Keyword(s):  
Quantitative Determination ◽  
Plasma Sample ◽  
Quantitative Measure ◽  
The Other ◽  
Clotting Time ◽  
Bovine Plasma ◽  
Autoprothrombin C

SummaryTwo quantitative procedures for autoprothrombin C are described. In one of these purified prothrombin is used as a substrate, and the activity of autoprothrombin C can be measured even if thrombin is in the preparation. In this procedure a reaction mixture is used wherein the thrombin titer which develops in 20 minutes is proportional to the autoprothrombin C in the reaction mixture. A unit is defined as the amount which will generate 70 units of thrombin in the standardized reaction mixture. In the other method thrombin interferes with the result, because a standard bovine plasma sample is recalcified and the clotting time is noted. Autoprothrombin C shortens the clotting time, and the extent of this is a quantitative measure of autoprothrombin C activity.

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